1. Field of the Invention
This invention relates in general to monitoring systems and more particularly to monitoring systems that monitor corresponding parameters of a plurality of components in a system, that clearly distinguish between information relating to normally encountered changes in operating parameter values and information relating to actual or pending failure states for a complex process, in an integrated display.
2. Related Art
In complex processes, it is desirable to monitor critical operating parameters or derivative values indicative of the state of the process. These “vital signs” are the quantitative representations of the time varying values of selected parameters, absolute or relative, directly monitored or indirectly derived from the monitored values which, taken together, provide an indication of the current “health” of the process. Two major indications of the state of the process are generally of interest:                1) Indications that operating parameters relating to the process are changing or have recently changed, typically as a result of human intervention in the process. This human intervention may take the form of adjustment or change of the characteristics of the process, or it may take the form of changes in inputs to the process. Both changes to the characteristics of the process and changes in inputs can be expected to propagate throughout the process as automatic controls detect the effects of the changes and respond to the detected changes in an attempt to maintain process stability. Such indicated changes in operating parameter values usually are of interest only in terms of automatic control system stability or of process history, although they can, under some circumstances, be seen as precursors of impending local or overall process breakdown.        2) Indications of existing or pending process faults due to component overload or failure as a result of control system instability or physical damage. Such indications are of immediate interest to the human operators responsible for overseeing the proper functioning of the process and serve to stimulate protective human intervention either to reconfigure the process or to shut it down completely to prevent further component damage or, conceivably, the development of potential hazardous conditions.        
In the past, visual displaying of the “vital signs” of a complex process was usually accomplished by the use of two independent monitoring and display systems operating in parallel. Thus, in a typical process control room, operating parameter values were usually indicated by analog or, more recently, digital, meters and changes in such values were detected by observing variations on graphical chronological records or in manually or automatically recorded periodic logs of prescribed sets of parametric values. On the other hand, indications of abnormal conditions or component failure appeared in the form of color coded lights on process mimics or as individually lighted message tiles on annunciator panels. More recently, a display system that combines both the process monitoring and the process alarming functions in driving a single, integrated, spatially organized textual display panel has been developed as described in U.S. Pat. No. 4,816,208. Due to unique application restrictions existing at the time this system was developed, the display was monochromatic and the distinction between normal changes in operating parameter values and abnormal state indications could be made only by assigning priorities to the predefined textual messages that could appear in given fields of the display panel. As a result, extensive training of the process operators in the interpretation of displayed information was required before the system could be used effectively.
A more flexible system is desired that would enable an operator to more readily integrate the data displayed to discern the state of the system. It is also desirable that the corresponding operating parameters of analogous components within the system be displayed together so their operating states can be correlated.
Thus, it is an object of this invention to provide a single, integrated parameter display that clearly distinguishes between information relating to normally encountered changes in operating parameter values and information relating to actual or pending failure states for a complex process.
It is a further object of this invention to provide such a display that identifies trends of critical process parameters.
It is an additional object of this invention to provide an integrated display that shows the recent past history of critical operating parameters.